Note 8. Shareholders' Equity (Detail) (USD $)	1 Months Ended	3 Months Ended				6 Months Ended		9 Months Ended			6 Months Ended	1 Months Ended	3 Months Ended	6 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2011	Sep. 30, 2012	Jun. 30, 2012	Sep. 30, 2011	Jun. 30, 2011	Sep. 30, 2012	Jun. 30, 2012	Sep. 30, 2012	Sep. 30, 2011	Nov. 02, 2012	Jun. 25, 2012 Restricted Stock Units (RSUs) [Member] June 2013 [Member]	Jun. 25, 2012 Restricted Stock Units (RSUs) [Member]	Sep. 30, 2012 Minimum Anticipated Annual Dividend [Member]	Jun. 25, 2012 2013 [Member]	Jun. 25, 2012 2014 [Member]	Mar. 31, 2012 Consent Decree [Member]	Dec. 31, 2011 Consent Decree [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in Shares)											262,934	440,735
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value														$ 1,900,000	$ 700,000
Stock Issued During Period, Shares, New Issues (in Shares)			77,976		42,636
Share-based Compensation								2,296,000	1,497,000
Stock Repurchased During Period, Shares (in Shares)						60,000		45,341
Stock Repurchased During Period, Value								200,000
Accelerated Share Repurchases, Final Price Paid Per Share (in Dollars per share)						$ 4.89		$ 4.47
Common Stock, Dividends, Per Share, Declared (in Dollars per share)		$ 0.0025		$ 0.0000				$ 0.0375	$ 0.0000				$ 0.01
Minimum Dividend Threshold (in Dollars per Ounces)							30
Average Realized Silver Price		35.00
Stock Repurchase Program, Authorized Amount						20,000,000
Stock Repurchase Program, Remaining Authorized Repurchase Amount						19,940,000
Share Price (in Dollars per share)										$ 6.49
Conversion of Stock, Shares Converted (in Shares)	2,012,500
Debt Instrument, Convertible, Conversion Ratio	9.3773
Stock Issued During Period, Shares, Conversion of Convertible Securities (in Shares)	18,900,000
Mandatory Convertible Preferred Stock Dividend	3,300,000
Proceeds from Warrant Exercises									$ 5,108,000							$ 700,000	$ 9,800,000